US2541362A - Reverting call circuit, all relay type - Google Patents

Description

Feb 13, 1191 R. W. JONES REVERTING CALL CIRCUIT, ALL RELAY TYPE 5 Sheets$heet 1 Filed Dec. 26, 1947 W T 6: 3; mi 62 m s E :2 W N J m M 0 R M M Y. B Q; Gm gomw xps fiwa 22 X755 9: g 228 final Feb. 13, 1951 R. w. JONES REVERTING CALL CIRCUIT, ALL RELAY TYPE 3 Sheets-Sheet 2 Filed Dec. 26, 1947 momm mmm

mm a warm EL LF ELM ENM M W m3 v3 mi NE @E NQE INVENTOR. ROY W. JONES @JTTORNEY Feb, 13, 1951 R. w. JQNES 9 9 REVERTING CALL CIRCUIT, ALL RELAY TYPE Filed Dec. 26, 1947 5 Sheets-Sheet 3 w M N mmvrox an m. JONES BY 7 Z wm W 3m 3 3M m; T

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ATTORNEY Patented Feb. 13, 1951 UNITED STATES PATENT OFFICE REVERTING CALL CIRCUIT, ALL RELAY TYPE Application December 26, 1947, Serial No. 793,995

3 Claims.

The present invention relates to automatic telephone systems in general and in particular to an improved reverting call circuit of the all relay type for use with party line systems in automatic exchanges.

An object of the invention is to provide a novel all relay type reverting call circuit which will provide more eificient operation.

A feature of the invention is the manner in which a reverting call switch is adapted to be seized over the all relay switch train and responsive to the receipt of impulses representing the suifix ring digits of the calling and called parties is operative to alternately apply the called and calling parties signals to the line and to release when the called party answers the signal whereby the conversation is carried on over the local line circuit and the reverting call circuit and the switch train may be reused.

A further feature of the invention is the manner in which a reverting call circuit of the type described is arranged to release responsive to a signal from the calling party, called party, or after a predetermined period of time.

Another feature of the invention is the manner in which one group of relays in the reverting call circuit is arranged to operate responsive to a first series of digits, transfer the received digit to a second group of relays, and reoperate responsive to a second series of impulses to register the second digit; and in which both groups of relays select the proper ringing signals represented by the two digits and apply the selected ringing signals to the line.

A further feature of the invention is the manner in which the reverting call system is arranged. to be used with exchanges connected for harmonic code ringing or for exchanges adapted for divided harmonic ringing by a simple strap adjustment.

Referring now to the drawing comprising Figs. 1, 2 and 3, the automatic telephone system there illustrated incorporates the features of the applicants invention as applied to a reverting call circuit.

Fig. 1 shows a plurality of substations connected to a party line. Stations A and B are connected for use with a code harmonic ringing system and stations C and D are connected for use with a divided harmonic ringing system. Fig. 1 also illustrates a line circuit, a finder, a connector with its associated trunk selecting relays, and a part of the reverting call circuit. Figs. 2 and 3 when properly arranged illustrate with Fig. 1 the circuit arrangement for the reverting call circuit.

The reverting call circuit is of the type which is seized over a finder-connector link on a switchthrough basis by dialing a, single digit assigned dicative of this type.

to the exchange for this purpose. When the reverting call circuit has been seized the subscriber first dials the last digit of his call number and then the last digit of the called partys number. Qn replacing his handset the reverting call circuit alternately applies the ringing signals for the called and calling parties to the line. When the called party enters, the switch train and the reverting call circuit are released and the conversation is carried on over the local line circuit.

The reverting call circuit as shown is arranged for use in exchanges using 10 party, 1 and 2 ring harmonic ringing, substations A and B being in- Slight modification as indicated by the dotted lines at contacts TI and [2 enable the arrangement for use in exchanges having 10 party divided harmonic ringing. Substations 0 and D are of this second type. The specification includes description for both arrangements.

Assuming, now, that a subscriber A desires to converse with a second subscriber B- who has his substation on the same line as A. The first subscriber A dials a special digit which is assigned to the reverting call relay circuit. The relay switch train in the exchange (shown in block form) operates to extend the call to the illustrated circuit over conductors I, 2 and 3 in a well known manner. The operation of extending the call to the reverting circuit and the subsequent operations by the subscriber are somewhat similar to those set forth in the Saunders Patent 1,805,726 issued May 19, 1931 on pages 18, 19, and 20 wherein the reverting call circuit eifectively uses .Strowger type switches.

More specifically, however, when the receiver is removed from the hookswitch at station A, a bridge is closed across the line conductors Isl and 192 in the usual manner and a circuit is thereby completed for the double wound relay H59 in the line circuit. Line relay I89 operates and at its contacts I82 connects ground to the C lead 93 to busy the line in the outgoing terminals of the connector switches. Marking ground for the finder distributor is connected by relay I 86 at its contacts 183 and I84. The finder-connector link maybe of the type shown in the Voss et al.

The finder also sends ground back over conductor I36 to operate cut-oil relay I and lockout relay I60 in series. Relay I'IIJ at contacts HI and H2 disconnects relay I89 from in bridge of the line and relay I80 releases. Relay I68 at contacts I62 and IE3 disconnects marking ground from thedistributor and prepares a locking circuit for itself at contacts IGI. At contacts [8i relay I88 connects ground from the finder to busy the connector terminal. nector switches are preferably of'theall relay switch-through type shown in the previously mentioned application of Voss etal. The connector circuit is shown in Figs. 6,7,8, 9 and 10 of the Voss et al. application. The trunk selecting relays for use therewith are shown in Figs. 11, 12, l3, l4. and of the Voss et al..application. The description in the Voss et .al. application under the heading Trunk calls is appropriate to the manner of operation of the link in completing a call to a trunk group by means of a single digit. In this case, revertive call circuits, as described herein, are connected to the connector terminals of connector I95 in lieu of the various trunk groups disclosed in the voss et al. application.

It is apparent that when the receiver is removed by subscriber A, the calling line is picked up by the finder switch ltd of a finder connector link and establishes a connection to the connector I95 which is thereafter under the control of the calling dial. When the subscriber dials the single digit assigned to the reverting call circuit, the connector switch I95 'operatesto extend the call to the reverting call'circuit.

When the reverting call circuit is seized over conductors I, 2 and 3 a loop is completed to line relay II]. The line relay Ii] operates and at its contacts II completes a circuit to relay 20, at its contacts [2 opens a further point in the circuit for relay Relay 25] operates and at its contacts 2 I connects ground to lead 3 over contacts QI to hold the preceding switch train, at its contacts 22 opens a point in the busy-circuit to the trunk selecting relays (shown in block form) to preventseizure by another party while the reverting call circuit is in use. Relay at its contacts 23 prepares a point in the operating circuit torelay 39 and the register relays, at its contacts 26 completes a circuit to the supervisory start relay (not shown) over lead 8 to start an associated timing circuit, at its contacts prepares a circuit for relay III] which is controlled by the associated timing circuit over contacts 25, I2I, HQ and lead I. At its contacts 26, relay 2% prepares a holding circuit for the'storage and register relays.

The calling subscriber now dials the ring digit suifix of the number assigned to his own substation and line relay Ill releases and operates responsive to the impulses. On the first release after seizure, relay Ill at its contacts II opens the operating circuit to relay 28. Relay 20 is slow to release and will hold during the break periods of each impulse. Relay I0 at its contacts I2 completes a circuit from the holding ground over contacts II2, I2, 23 and I3I to relay 3B, and to the upper winding of relay I20. A circuit is also completed to the first register relay 230 over contacts II2, I2, 23, I3I, 213, 283 and 293. Relay 38 operates, at its contacts 3I completes an operating circuit to the lower winding of relay I20, and at its contacts 32 and 33 opens further points in the line ringing circuit. Relay I28 operates and at its contacts I2I The conopens the circuit from the associated timing circuit to relay I It and at its contacts I22 opens a point in the operating circuit to storage relays 3) to 350. Register relay 20E] operates, at its contacts ZIJI prepares a point from the generator lead I8 which supplies one ring service to relay 'iELand at its contacts 2532 prepares a ringing circuit for negative side of the line by connecting ground to the positive side of the line. This arrangement is applicable in the event that divided ringing is used. Relay 2% at its contacts 253 prepares a circuit from generator I to ring over the negative side of the line, at its contacts 285 prepares a circuit to the first storage relay can, at its contacts prepares an operating circuit for the second register relay 2IIl, and

at its contacts 205 completes a self holding circuit and an operating circuit for control relay 29I over contacts 285, line 23L contacts 3m, line I52, contacts c and 2il. Relay 29I will not operate however because of the multiple ground circuit controlled by the line relay contacts I2 which is completed to the first register relay 2530 at the time. However, when the make period of the succeeding impulse is received over the line, line relay It operates and at its contacts l2 opens the multiple ground circuit to relay 28S and relay 29% operates in series with relay 2336. The operating circuit to relay 30 is also opened, but relay 3t is a slow to release relay and holds during the impulse series. At its contacts 292 relay 2% prepares a circuit to relay iEil, at its contacts 293 opens a further point in the operating circuit to relay ZOIL'at its contacts 2% prepares an operating circuit for the second register relay 2H], and at its contacts 235 opens a further point in the circuit to relay 2? I. On receipt of the break period of the second impulse a circuit is completed for the second register relay 2H3 over contacts H2, I2, 23, I3I, 213, 283, 2% and 2&5. The register relay Zlll operates and at its contacts 2I5 prepares a circuit for relay 2213 at its contacts-2H3 prepares a circuit for control relay 23L Relay 28! operates when the multiple ground circuit to relay ZIIl is opened by the line relay IS at its contacts I2 on receipt of the succeeding make period. The control relay 2 BI operates and at its contacts 284 prepares a point in the operating circuit to the next register relay 220, and at its contacts 285 opens the holding circuit to the first register relay 2% and the control relay 29I. Relays 26d and 29l release. Relays 2H] and 28I remain operated over the holding circuit'comprising contacts 266, 215, line 23?,contacts Sill, lead I52, contacts as and 25. It is obvious from this description that each succeeding impulse-operates a further register relay and the control relay associated therewith which effects release of the previously operated register and control relays.

Assuming that the digit dialled by the subscriber was 7, register relaysZilil, 25$ 22G, 2st, 246, 252 and 2% will operate with their associated control relay as just described. Additionally, when relay 259 operates, at its contacts 25? a circuit is completed for storage relay 350 over contacts 257, line 23%, contacts ti l, and 28. Relay 36!] operates and at its contacts 3% opens apoint in the 1 ring lead from the interrupter to ringing interrupter relay ill, and at its con tacts .362 closes apoint in the 2 way interrupter circuit to relay l6. Relay 3% at its contacts 363 opens 'point in the ground connection to the negative side of the line, at its contacts 366 prepares a ground connection to the positive side of the line, at its contacts 364 prepares a point in the ringing circuit to the negative side of the line, and at its contacts 365 opens a further point in the ringing circuit to the positive side of the line This transfer of ground connections from one side of the line to the other is effective in the event that divided line ringing is desired. It is apparent from the storage relay contact connections that digits l5 of the calling parties numbers are rung over one side of the line and digits 6-0 are rung over the other side. If 1 ring and 2 ring service is desired for bridged ringing, it is apparent that relay 360 at its contacts 36I effects one ring signal for digits 1-5 and at its contacts 362 effects a 2 ring signal for digits 6-0. The use of storage relay 360 enables the circuit to use 6 relays to store any one of ten different digits. Relay 360 at its contacts 36'? completes a self holding circuit over contacts 35f, line H52, contacts 95 and 26. The operating circuit to relay 360 is opened at 'contacts 2% when relay 250 is released responsive to receipt of the seventh break period. The succeeding register relay 260 is operated as described heretofore and at its contacts 264 prepares a circuit to the second storage relay 320. Control relay 291 is also in the operated condition.

On termination of the incoming impulses, line relay Iii remains energized and at its contacts i2 holds open the operating circuit to relay 39. After a brief interval relay 3i) releases and at its contacts 3i opens the operating circuit to the lower winding of relay IZii. The holding circuit for the upper Winding of relay I20 is also open at contacts 52 of the line relay. Relay I29 releases and at its contacts I2I completesa circuit from the timing equipment to relay I It, and at its contacts I22 completes an operating circuit to storage relay 320 over contacts 26, 95, i22, lead ltd, contacts 313, lead 248', contacts 26% and lead 256. Storage relay 320 operates, at its contacts 32I completes a circuit to relay at its contacts 322 prepares a point in the circuit from generator 2 to the negative side of the line and at its contacts 323 prepares a self holding circuit through relay 310, lead I52 and contacts Q5 and 28. Relay 310 is short circuited by the operating circuit which is completed to storage relay 22c. Relay 3% operates and at its contacts till opens the holding circuits for register relay and control relay 29I. Relays 260 and 29! release. Relay 2% at its contacts 264 opens the original operating circuit to storage relay 329, which effects operation of relay 310 by removing the short circuit on same. Storage relay 320 holds over the holding circuit described. Relay 310 at its contacts 3H opens the operating circuit to relay tilt, at its contacts 312 prepares a circuit for transfer relay I30, at its contacts 313 opens a further point in the operating circuit for the storage relays and at its contacts 314 opens the operating circuit to relay 360 which holds over a self holding circuit comprising contacts 361, lead $52, contacts 95 and 26. Relay 300 releases and at its contacts 3! prepares the register relays for receipt of the next series of impulses.

It is apparent that the calling subscriber has seized the reverting call circuit and'dialled the ring digit sufiix assigned to his own substation and thereby effected operation of the register relays in the reverting call circuit. The register relays have operated in sequence responsive to each impulse and upon completionof the receipt 6 of the digit efiected a, transfer of the digit received to a set of storage relays. The storage relays select the frequency for signaling the calling party and selects the 1 ring or 2 ring interrupter lead for ringing purposes or in the event that divided ringing is being employed, they select the side of the line to be rung. Further, the register relay and control relay which were operated to accomplish the results described are released to thereby prepare the set for receipt of the called ,partys digit and to prepare the register relays for reuse in handling the called partys digit. Relays It, 20, 320, 360 and 310 are now in the operated condition.

The calling subscriber now dials the station suffix digit of the called substation and line relay It operates in response thereto. On the first impulse relays 30, I26 and 260 are operated in the manner heretofore described. Assuming that the subscriber dialled the digit 3, the register relay 220 and control relay 2 will be in the operated condition on termination of the impulses representing the digit 3. Relay 220 at its contacts 22f prepares a circuitfrom the 1 ring interrupted lead to ring interrupter relay it and at its contacts 222 prepares a circuit for ringing over the negative side of the line by completing a point in the ground connection to the positive side of the line. At its contacts 223, relay 22f] completes a point in the circuit from generator 3 to the negative side of the line for signaling the called party and at its contacts 224 prepares a circuit to the storage relays which is ineffective at this time in that relay 370 at its contacts 3'53 maintains the circuit open whenever a storage relay is in the operated condition. It is apparent,

from the register relay contact connections that if the called partys digit is from 1 to 5, the called partys frequency will be applied over the negative side of the line and if the digit is from 6-0 the called partys frequency will be applied over the positive side of the line. Further, if 1 ring and 2 ring service is being used, digits 1 to5 inclusive are rung once. Although digits 6-0 utilize the same five frequencies used for the first five digits, the connections are such that a 2 ring interrupter lead is connected to the ringing interrupter relay. The generator frequency y to be used is selected by the register relay remaining operated responsive to the digit received, in this case contacts 223 on register relay 220. At its contacts 225, relay 22c prepares a circuit for register relay 232 and at its contacts 225 prepares a circuit for control relay 2H which operates when the line relay It energizes following termination of the series of received impulses representing the called partys digit.

A short interval after receipt of this digit, relays 3t and E28 release, the holding circuits for same being opened at the line relay contacts l2. Relay I26 at its contacts I22 completes a circuit to relay I30 over contacts 26, 55, I22, lead I53, contacts 3'52, lead 2 59, contacts 272, and lead 249. Relay Ittoperates and at its contacts I32 prepares a circuit to relay 40, and at its contacts I3! opens a further point in the circuit to relays 30 and i251 to prevent their subsequent operation. Relays iii, 25, E36, ill, 220, 320, 382 and 310 are in the operated condition.

The calling party now replaces his handset and thereby effects deenergization of line relay "i3 disconnectstheline-relay w from the incomlug-dine; at its contacts' ltanddfi completesa *point'in the circuitfrem the incoming line-to "the ringing circuits, andatits contacts 35 completes a holding circuit for-relay *29 over contacts- H2 :andd i. Relay' ZS is slow-to release and remains operated until- -this holding circuit is-com'pleted thereto and thereby prevents r13- lea-se of the preceding opera-ted switch train and line 'circ-uit cutoti-relay ii-t. -Atitscontacts i6, relay 4i) completes a circuit to the-motor-start relay 'over'lead s *to start-the interrupter, at its contacts '4?- prepares a holding circuit for Y pickup relay I68, at its contacts completes a-circuit from the interrupter pickup lead ism pickup relay HEEL and at its contacts iil connects interrupter-lead i6-to relay 3'. Lead ii is connected to ground in-the ringing interrupter on alternate code'cy-cles; Relay 53f] therelore will energize for onecode cycle and restoreior the duration of the next code cycle. At the beginning of a ring 'ing cycle ground is connected for a short interval of time-over pickup lead 55 and contacts ditto relay H30. Relay H16 operates and at its'contacts IOI completes a circuit to ringing interrupter .relaylc and at its contacts i532 completes a selfholding circuit over contacts ll and W2.

A ground pulse is supplied to relay ll? by the interrupter over the one ring lead l8,-contacts 83, lead hi6, contactsZZi, and contacts 543i. Relay l'l! operates to connect the ringing circuit to the incomingline'overcontacts c2 and id, 7! and i2, "8lnand"3,33, 222 and223 and a ground and generator connection. it is seen therefore that .ithe called partys signal, which in this case is represented by a single ring of the frequency of generator three, is transnntted over the negative :side of the line. If the phones are bridged across thetline, the two ringers responsive to the frequency of generator three will rin once, and the one party to whom the one ring si nal was assigned .will answer. The party who has been 'assigneddigit 8 will answer when 2 rings of the .frequency output of generator three are applied -.to the line. In-the event that the dotted connections, which are shownas by-passing contacts H andl'i2, are utilized, ringing interrupter relay Hi will be'ineffective. The ringers, if connected to the line-for use in a divided ringing arrangement, will be operated when the proper frequency is applied to the proper side of the line. lhus, with five frequency generators, five substation sets each with a different frequency can be used on one side of the line and sets responsive to those same five frequencies can be employed on the other side of the line.

When lead it is connected to ground by'the interrupter on the subsequent code cycle, relay 80 will operate and at its contacts 82 and--84 connect a second ringing circuit to the line over contacts 42 and 44, H and i2, 82 and 86, lead 155 and 55, contacts 35 and 365 to ground, 322, lead 216, 286 and 296, and generator '2. Relay '86 at its contactsild connects the two ring interrupter ground to relay ii! over contacts 85, lead lEl, contacts. 352-and 195. Relay lfloperates twice, and on each operation connects the ringing frequency of generator two to the line to signal the calling party. The ringing frequencies are alternately applied to the line to thereby repeatedly signal the called party and the calling party.

IWhenthe call is answered, relayifl or'relay '60 will operate and at their contactsfil or-BI co-mpletela circuit to. relay 96. Relay 90cperates' --'-an'd =at its= corrtacts--9lopens-*theholdi-ng ground circuit to *the' preceding finderconnector link to release-"the same, at its contacts 92 completes a self holding circuit over contacts- 2! and 92, at *its contacts 93 opens-a further pointin the busy 'ci-rcuitover-lead d to prevent seizure before the =revert-ing-call circuit is completely released, at itscontacts 9% opens the operating circuit to re laydfigand-at-its oontacts 'fi i opens the holding .10 circuit to the operated storage relaytZ 9' and 358, "the 'operated'register relay 229, the operated "control-relayElL-relay I39," and relay 3%. -Re- "layscamera-22a, 2H, 139, 37c release. Relay 'fi releases and at its-contacts'dl-and 33 reconnects'the line relay "Hi-totheincorning line con- -ductors,'at its contacts 52 andi t disconnects the ringing circuits to the line and also opens the operating circuit to relays 5E3 andfidatits con- *tacts i opens the hol'dingcircuit to relay 2i], "atits 'contacts i opens "the" circuit to the relay "which operates the interrupter, at its contacts lirand 6? opens the'operatingandholdingcircuit-stor-relay H38, and at contacts i-S opens the circuit-to relay" BS. "Relays- 5c;ec-,- sc and Hit re- 'lease. Relaylil releases on' removal of the interrupterground or when the operated storage or register relay releases. Relay '2i2- releases and at -its contacts 2| opens-"the holding circuit to relay 9%. Relay Q6 releases and the reverting call set is available'for further use by other-party lines.

' When the ground is rernovedfrom the lead 3, thefinder-connector link-releases and removes "ground from conductor 185 to open'the'oircuit ,235 vo'cut off re-lay E79 and lockoutrelay sec and "cut-ofi relay ilfi'releases. Line relay Hit then energizes over contacts-lit and H2 andthe line bridge'wh-ich is completedbythehooliswitch at the answeringpartys substation and at its con- 40 tacts' l ficonnects ground 'to'the C'lead iiiii'to mark the lineousy to the connectors. Line relay lSSa-tcontacts E83 completes a holding circuit byway of contacts lti before the slow to release lockout relayifiii has'ha'd-sufficient time to release withthe result-that relay aecis nowmain- --tained energized-by line relay use to open the niarlring -leads to i the distributor.

Talking-"battery is fed to the" line through the "windings of'the line relay H88" and the line cir- *cu-it-is therefore theonlyequipment'in useduring the-conversation eetween the parties.

Release of-the line circuitis eiiected when 'the last -party hangs up. -Re1aylBElreleasesand at =its contacts i 83- opensthe holding circuit to relay4 6d Relay l idrestores andthe line circult-is in' its normal condition.

In the event that a callwas'init-iatedbutnot completed through the reverting call circuit, it -willbe-released-after a predetermined time inuoterval after-seizure by operation-cf an associated timing circuit. The timing circuit is started on seizure-of thereverting call circuit at contacts 2 3 on relay-2ii. "The timing equipment 'transnii-ts agroundedpulse over lead? after a capredetermhred time interval to operate relay "H5. Relay- H9 operates and at its contacts ill and i is transfers the holding ground for the revertingcallset to the-timer equipment over lead fi a'nd at its-contacts H3 and lit opens its operating circuit from the timerand completes a self holdin circuit overtcontacts 3,42! .and :5. IIWhenthe predetermined time has elapsed, the lchclding ground is removed from lead 5 to -openthe; circuit toz. relay ZIt Which releases and restores the-revertingcall circuit and the finder- 9 connector link to normal by removing ground from conductor 3 which has been holding the link in an operated condition. The release of the finder-connector link restores line relay l and also removes ground. from conductor I86 to restore cut-01f relay iii! and cause the operation of line relay ififi while lockout relay I60 is retained in the operated position. The line circuit therefore remains in the look-out condition until the party initiating the call replaces the receiver. In the event the called party does not answer after being signalled the calling party may lift his receiver which will effect operation of relays 59 or 56 as heretofore described and the reverting call circuit will be restored to normal or if both the called and calling parties fail to answer, the timer circuit will effect release of the circuit after a predetermined time.

Timing out in case both the called and calling parties fail to remove their receivers is accomplished automatically. It will be remembered that relays 20, so, we, H0, its, 27!, 2283, 32B, 360 and 31B are in the operated condition. The holding ground for the circuit is connected over contacts H2. After a predetermined time, ground is applied to conductor 1 to operate relay H9. Relay HE? locks to ground over contacts H3, l2! and 25 and at its contacts I I l transfers the holding ground to the timer circuit over lead 6. After a further predetermined time, ground is removed from lead 6 and the reverting call circuit will restore to normal as previously described.

While a particular embodiment of the invention has been described, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention.

What is claimed is:

1. In a reverting call circuit for use with a party line system using harmonic ringing and having substations connected in bridge of said line, an incoming line, a line relay operated responsive to impulses received over said incoming line, a group of register relays operated in succession responsive to the successive operations of said line relay, means for maintaining one of said register relays in the operated condition on termination of a first impulse series in accordance with the number of impulses received, a group of storage relays, said register relays divided into pairs of relays for controlling said storage relays, means controlled by each pair of said register relays to complete a point in the operating circuits for each of said storage relays, said point in said operating circuit to a storage relay completed whenever either one of said pair of register relays is in the operated position, a transfer relay automatically operated on termination of said first impulse series to complete a circuit to one of said storage relays over the operating circuit prepared by the register relay in the operated condition, means controlled by said storage relay to release the operated register relay and to complete a self holding circuit, said register relays reoperated in succession responsive to the operation of said line relay by a second series of impulses thereto, means for maintainoperated storage relay to select the frequency and code ring circuits to signal the calling party, and means controlled by reoperation of said transfer means responsive to the termination of said second series of impulses to prepare to alternately connect each of the selected ringing signals to the line. i

2. In a reverting call circuit for use in a party line system using divided harmonic ringing, an incoming line, a line relay operated responsive to impulses received over said incoming line, a group of register relays operated responsive to operation of said line relay by a first series of impulses, a group of storage relays, means controlled by each of said register relays to prepare the operating circuit of a storage relay, means for completing a circuit to one of said storage relays over the operating circuit prepared by the register relays after the termination of said first series of impulses, means controlled by the storage relays to then release the operated register relays, means for maintaining said storage relay operated on release of said register relays and the completed operating circuit, said group of register relays reoperated responsive to the operation of said line relay by a second series of impulses, means for maintaining one of the register relays in the operated condition, a plurality of frequency sources, means controlled by the operated register relay to select a frequency and side of the line for signaling the called party, means controlled by said operated storage relay for selecting the frequency of the calling party, a control storage relay having an operating circuit controlled by only one of said register relays, means controlled by said control storage relay for selecting the side of the line for signaling the calling party, and means for alternately applying the selected frequencies for the called and calling parties to the line. I

3. In a reverting call circuit for use in a party line system for enabling one party to call another on the same line, an incoming line, a line relay operated responsive to series of impulses received over said line, a group of register relays operated responsive to operation of the line relay by a first series of impulses indicative of the calling partys numberfone of said register relays maintained operated on termination of the first series of impulses in accordance with the number of impulses received, a group of storage relays, circuit means controlled by said operated register relay for controlling operation of" an associated storage relay, means for operating sa d storage relay over said circuit means and maintaining it in said operated condition after release of the operating circuit to thereby effectively store the set of impulses indicative of the calling partys number, means operated by said storage relay to release said operated register relay, said register relays reoperated responsive to operation of the line relay by a second series of impulses indicative of the called partys number, one of said register relays maintained operated on termination of the second series of impulses in accordance with the number of impulses received, a plurality of sources of frequencies, a plurality of code ring circuits, means controlled by the operated register relay for selecting the frequency, the code ring circuit and the proper side of the line for ringing the called party, means controlled by the operated storage relay for selecting the frequency, the code ring circuit, and the proper side of the line for ringing the calling party, means for connecting the code ring and :11 12 the frequency selected to comprise the signals UNITED .STA'IES PATENTS forthe parties-to the line,and.cross connecting Number Name Date means-for.making the code ring ineffective where- 1 321 Lundeu Apr 1923 upon the "parties are signalled by means of'the 1849087 Hovland 1932 frequency and side of theline selected, and means 5 2187186 Wallace Jan 16 1940 for alternately connecting the calling and called 2325877 Powell 1943 parties signals to the line as selected in accord' 2443945 Bellamy" June 1948 ance-with the existingeconnections.

ROY JONES OTHER'I REFERENCES 10 Smith and Campbell, Automatic Telephony, REFERENCES-CITED McGraW-Hill, 1921, page 313.

The following references are of record in the file of this patent:

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